1. Field of the Invention
The present invention relates to charging circuits, and particularly to a charging circuit which is used in a portable device and configured to charge electronic devices.
2. Description of Related Art
Nowadays, some portable devices such as notebook computers are capable of recharging other electronic devices such as mobile phones and MP3 players. However, these portable devices can only recharge other electronic devices when they are turned on. If they are turned off, they have no charging function available.
What is desired, therefore, is to provide a charging circuit of a portable device which can recharge electronic devices even when the portable device is turned off.